Preparation of thermoset cycloolefin polymers via metathesis catatysis is a relatively recent development in the polymer art. Klosiewicz, in U.S. Pat. Nos. 4,400,340 and 4,520,181, teaches preparation of such polymers from dicyclopentadiene and other similar cycloolefins via a two-stream reaction injection molding (RIM) technique wherein a first stream, including the catalyst, and a second stream, including a catalyst activator, are combined in a mixhead and immediately injected into a mold where, within a matter of seconds, polymerization and molding to a permanently fixed shape takes place simultaneously. The thermoset polymers produced have physical properties making them suitable for structural and electronic applications. In such RIM processes, it is important that the polymerization reaction occur rapidly and with as complete incorporation of the charged monomers as possible. It has been found that in molding polydicyclopentadiene, for example, that the presence of unreacted monomer results in a molded part of a very unpleasant odor and less than optimum physical properties. In commercial RIM processes, it is also economically desirable that the process be carried out in as short a cycle time as possible.
In the typical system, according to Klosiewciz, the catalyst component is a tungsten or molybdenum halide and the activator is an alkyl aluminum compound. Most strained ring non-conjugated polycycloolefins are metathesis polymerizable. The preferred cyclic monomer is dicyclopentadiene or a mixture of dicyclopentadiene with other strained ring hydrocarbons.
The preferred catalyst component as taught by Klosiewicz is a tungsten halide, and preferably a mixture or complex of tungsten hexachloride (WCl.sub.4) and tungsten oxytetrachloride (WOCl.sub.4). The tungsten or molybdenum compound of Klosiewciz is not normally soluble in the cycloolefin, but can be solubilized by complexing it with a phenolic compound.
In U.S. Pat. Nos. 4,981,931 and 5,019,544 tungsten catalyst compositions for metathesis polymerization comprising: ##STR1## where X is Cl or Br, n is 2 or 3, R.sup.1 is H, Cl, an alkyl group having 1-10 carbons, an alkoxy group having 1 to 8 carbons, or a phenyl group, R.sup.2 is H or an alkyl group having 1 to 9 carbon atoms and R.sup.3 is H or an alkyl group having 1 to 10 carbon atoms for use with tri-n-butyltin hydride or a triphenyltin hydride activator, are disclosed. Both the catalyst and activator compounds are disclosed to have improved stability with resistance to oxygen and moisture. It is indicated the catalyst compounds are easy to isolate instead of being mixtures as those found in the prior art.
More recently, U.S. Pat. No. 5,082,909 discloses a process for preparing a polymer which comprises contacting a strained ring polycyclic polyolefin with a substantially pure tungsten complex, having the formula WOCl.sub.4-x (OAr).sub.x, wherein OAr represents a mono, di, tri, tetra or penta-substituted phenoxy group and where x=1, 2, or 3. These catalysts are indicated to be efficient in promoting ring-opening metathesis polymerization of dicyclopentadiene (DCPD) at lower catalyst concentration levels than previously achieved.
Recent publications have disclosed that tungsten and molybdenum imido-alkylidene complexes, e.g., M(NAr)(CHR)(OR).sub.2 (=Mo or W), can be used for ring-opening metathesis catalysis resulting in the preparation of linear polymers and polyacetylenes. In these cases, the M(NAr)(CHR)(OR).sub.2 species are regarded as very active unicomponent ROMP catalysts. Schrock et al in J. Am Chem. Soc. 110, 1423 (1988) describe a number of tungsten complexes of the stoichiometry W(OR').sub.2 (=CHR") (NAr'), where OR' is selected from alkoxide (e.g., OCMe.sub.3), thiophenylalkyl (e.g., SC.sub.6 H.sub.3 -2,6-i-Pr.sub.2), phenoxide (e.g., OC.sub.6 H.sub.2 -2,6-i-Pr.sub.2) fluoroalkoxide (e.g., OC(CF.sub.3).sub.3), and Ar' is a substituted aromatic ring, such as 2,6-diisopropylphenyl or 2,6-dimethylphenyl. A number of methods have been previously disclosed for the preparation of tungsten-imido-alkylidene complexes. However, all of these methods provided for separate preparation of such alkylidene complexes prior to addition to the monomer. For example, the original preparation of W(CHC(CH.sub.3).sub.3)(NAr)(OC(CH.sub.3).sub.2 (where Ar=2,6-diisopropylphenyl) was achieved by reacting W(CHC(CH.sub.3).sub.3 ) (NAr) (dme)Cl.sub.2 (where dme is dimethoxyethane) with two equivalents of lithium tert-butoxide. The W(CHC(CH.sub.3).sub.3) (NAr) (dme)Cl.sub.2 was prepared by a five step reaction as described by Schaverian et al. in the Journal of the American Chemical Society, 1986, 108, 2771-2773. The reaction involved the reaction of three equivalents of CH.sub.3 OSi(CH.sub.3).sub.3 with WCl.sub.6 to produce W(OCH.sub.3).sub.3 Cl.sub.3. W(OCH.sub.3).sub.3 Cl, was then reacted with six equivalents of (CH.sub.3 CCH.sub.3)MgCl in ether to produce W(CC(CH.sub.3).sub.3)(CH.sub.2 CCH.sub.3).sub.3. W(CC(CH.sub.3).sub.3) (CH.sub.2 CCH.sub.3)).sub.3 was in turn reacted with three equivalents of HCl in dimethoxymethane to achieve W(CC(CH.sub.3).sub.3) (dme)Cl.sub.3. This last product was reacted with trimethylsilyl-2,6-diisopropylphenylamine(ArNHTMS) to produce W(CHC(CH.sub.3).sub.3) (NHAr) (dme)Cl.sub.2. The final step in the sequence is completed by the reaction of W(CHC(CH.sub.3).sub.3)(NHAr)(dme)Cl.sub.2 with (CH.sub.3 CH.sub.2).sub.3 N in ether to produce the desired product of W(CHC(CH.sub.3).sub.3) (NAr) (dme)Cl.sub.2. The most recent synthetic strategies have been outlined by Schrock et al. in Organometallics, 1990, 9, 2262-2275. There are other routes available for the preparation of tungsten-imido alkylidene complexes (L. K. Johnson; S. C. Virgil; R. H. Grubbs; J. W. Ziller. J. Am. Chem. Soc. 1990, 112, 5384-5385.), but they also require the use of severe chemicals and laborious multi-step preparations.
As indicated above, the previous reaction schemes involve the preparation of complexes as a process separate from the polymerization process. In addition, the previous complexes have not been used for polymer synthesis where a two (or more) component system, such as in reaction injection molding (RIM) is used.